I am using IE on poweruser account w2k. After visiting bunch of porn/warez sites I didn't catch any malware.

IE is secure? NO
I'm good in blocking malware? NO
I use Spybot S&D TeaTimer? Yes

My answer on main question in this thread is:
Any app is secure if you know how to secure it, or if you use another security tools with it.

Advice:
Try both IE and Mozilla. See what is easier to use, more confotable. Then decide what you will use in the future. After that, secure your box. How to secure it? try to read security tutorials on AO for example.
No matter what you use for browsing, don't forget AV, patching, firewall, patching, malware scaners, patching, reading security tutorials, patching, not using admin account when browsing, patching, etc.